Process for producing light-diffusing methacrylic resin article

Abstract

A process for producing a light diffusing methacrylic resin article consisting essentially of a substrate polymer and crosslinked polymer beads having an average particle diameter of 1-16 mu m dispersed therein, the difference between the refractive indexes of the crosslinked polymer beads and the substrate polymer being 0.02-0.15, which comprises compounding the crosslinked polymer beads with: (A) methyl methacrylate or a mixture of a major amount thereof with a minor amount of at least one comonomer; (B) at least one monomer which can form a polymer compatible with the polymer obtained from (A); or (C) a polymer-in-monomer solution obtained by partially polymerizing either the (A) monomer or the (B) monomer, to swell the beads until a degree of swelling of from 120% to 1,500% is reached, and subjecting the resulting mixture to polymerization to obtain a light diffusing polymer and molding the polymer alone or in combination with a methacrylic resin, the main monomer unit of which is methyl methacrylate to a desired shape. The article obtained has a good balance between brightness and maximum bend angle, has such an opacity that a light source is not seen through the article and has a good appearance.

What is claimed is: 
     
       1. A process for producing a light diffusing methacrylic resin article consisting essentially of a substrate polymer and crosslinked polymer beads having an average particle size of 1-16 μm dispersed therein, the difference between the refractive indexes of the crosslinked polymer beads and the substrate polymer being 0.02-0.15, which comprises compounding the crosslinked polymer beads with: (A) methyl methacrylate or a mixture of a major amount thereof with a minor amount of at least one comonomer;   (B) at least one monomer which can form a polymer compatible with the polymer obtained from (A); or   (C) a polymer-in-monomer solution obtained by partially polymerizing either the (A) monomer or the (B) monomer, to swell the beads until a degree of swelling of from 120% to 1,500% is reached, and subjecting the resulting mixture to polymerization to obtain a light diffusing polymer and molding the polymer alone or in combination with a methacrylic resin, the main monomer unit of which is methyl methacrylate to a desired shape.     
     
     
       2. A process for producing a light diffusing methacrylic resin article according to claim 1, wherein the molding is effected by extrusion molding, press molding or injection molding. 
     
     
       3. A process for producing a light diffusing methacrylic resin article according to claim 1, wherein an average particle diameter of the crosslinked polymer beads in a range of from 3 μm to 12 μm. 
     
     
       4. A process for producing a light diffusing methacrylic resin article according to claim 1, wherein methyl methacrylate is compounded with the crosslinked polymer beads. 
     
     
       5. A process for producing a light diffusing methacrylic resin article according to claim 1, wherein a polymer of methyl methacrylate having a polymerization conversion of 20% is compounded with the crosslinked polymer beads. 
     
     
       6. A process for producing a light diffusing methacrylic resin article according to claim 3, wherein methyl methacrylate is compounded with the crosslinked polymer beads. 
     
     
       7. A process for producing a light diffusing methacrylic resin article according to claim 3, wherein a polymer of methyl methacrylate having a polymerization conversion of 20% is compounded with the crosslinked polymer beads. 
     
     
       8. A process for producing a light diffusing methacrylic resin article according to one of claims 1 to 7, wherein the crosslinked polymer beads consist of a copolymer of a phenyl group containing vinyl compound with a polyfunctional monomer copolymerizable therewith. 
     
     
       9. A process for producing a light diffusing methacrylic resin article according to one of claims 1 to 7, wherein the crosslinked polymer beads consist of a copolymer of a phenyl group containing (meth)acrylate with a polyfunctional monomer copolymerizable therewith. 
     
     
       10. A process for producing a light diffusing methacrylic resin article according to claim 8, wherein the phenyl group containing vinyl compound is styrene. 
     
     
       11. A process for producing a light diffusing methacrylic resin article according to claim 9, wherein the phenyl group containing (meth)acrylate is phenyl methacrylate. 
     
     
       12. A process for producing a light diffusing methacrylic resin article according to claim 8 wherein the polyfunctional monomer is divinylbenzene. 
     
     
       13. A process for producing a light diffusing methacrylic resin article according to claim 8 wherein the polyfunctional monomer is ethylene glycol dimethacrylate. 
     
     
       14. A process for producing a light diffusing methacrylic resin article according to claim 8 wherein the polyfunctional monomer is allyl methacrylate. 
     
     
       15. A process for producing a light diffusing methacrylic resin article according to claim 8, wherein the phenyl group containing vinyl compound is styrene and the polyfunctional monomer is divinylbenzene. 
     
     
       16. A process for producing a light diffusing methacrylic resin article according to claim 8, wherein the phenyl group containing vinyl compound is styrene and the polyfunctional monomer is ethylene glycol dimethacrylate. 
     
     
       17. A process for producing a light diffusing methacrylic resin article according to claim 9, wherein the phenyl group containing (meth)acrylate is phenyl methacrylate and the polyfunctional monomer is allyl methacrylate. 
     
     
       18. A process for producing a light diffusing methacrylic resin article according to claim 9, wherein the polyfunctional monomer is divinylbenzene. 
     
     
       19. A process for producing a light diffusing methacrylic resin article according to claim 9, wherein the polyfunctional monomer is ethylene glycol dimethacrylate. 
     
     
       20. A process for producing a light diffusing methacrylic resin article according to claim 9, wherein the polyfunctional monomer is allyl methacrylate.